1. Field of the Invention
The invention relates generally to a microwave shield for a food container. More particularly, the invention relates to a microwave shield that is pre-applied to a sheet of cover material, and a method of application to a food container.
2. Description of Related Art
Pre-packaged microwavable meals, also called xe2x80x9cTV-dinnersxe2x80x9d usually contain a variety of different foods; e.g. meat, potato, mixed vegetable, and dessert. These foods cook at different rates in a microwave oven due to the rate at which they absorb microwave energy as well as their individual heat capacities.
Microwave shields are often provided to prevent over cooking of high-absorbing food products. These shields are provided in a variety of forms; sometimes they are provided separately in the box with a TV-dinner for placement by the consumer prior to cooking. Otherwise the shield may be in the form of an enclosure within which the TV-dinner is wrapped or inserted by the consumer prior to cooking. These types of microwave heat shields are cumbersome to use and expensive to manufacture.
It would be preferred to provide a microwave shield directly to a microwavable food container during a manufacturing process thereof. Preferably, such a microwave shield would be applied such that it selectively shields certain high-absorbing foods while leaving other low-absorbing foods more substantially exposed to microwave irradiation. Most preferably, such a microwave shield is pre-applied to the cover member of a microwavable food container or tray.
A method is provided for providing a microwave-shield to a microwavable food tray having different foods therein requiring different degrees of microwave irradiation. The method has the steps of: (a) providing a microwavable food tray containing at least one low-absorbing and at least one high-absorbing food component, the low-absorbing food component requiring a greater degree of microwave irradiation to be heated to a desired temperature at the end of a microwave cooking cycle than the high-absorbing food component, wherein the food tray has a cover member thereover to cover the foods in the food tray; and (b) adhering a microwave shield to the cover member of the food tray, the microwave shield being applied to the cover member substantially in register with the high-absorbing food component, wherein the microwave shield has a shape substantially corresponding to the shape of the high-absorbing food component, and is effective to divert a portion of incident microwave radiation away the high-absorbing food component during a microwave cooking cycle.
A method for providing a cover member having a microwave-shield already attached thereon to microwavable food trays having different foods requiring different degrees of microwave irradiation is also provided. The method has the steps of: (a) providing microwavable food trays having at least one low-absorbing and at least one high-absorbing food component, the low absorbing food component requiring a greater degree of microwave irradiation to be heated to a desired temperature at the end of a microwave cooking cycle than the high-absorbing food component; (b) providing a sheet of food tray cover material having a plurality of microwave shields applied thereto and indexed at discrete intervals along the length thereof; and (c) delivering the food trays successively to a cover applicator machine in a microwavable food packaging process, wherein the cover applicator machine draws cover material from the sheet and applies therefrom a cover member having a microwave shield to each food tray, wherein the indexing interval facilitates application of a cover member to each food tray in the packaging process. Each microwave shield is applied substantially in register with a food component in each tray.
A sheet of microwavable food tray cover material is also provided having a plurality of microwave shields applied to and indexed at discrete intervals along the length thereof.